– PREPARING FOR A GREEN ROOF

Jun.24,2012

The first day of Summer 2012, perfect weather to install CTEM Waterproofing. Well, maybe for the CTEM but for us it was way too hot. Well at least we had a great view while working. For this Long Island home designed by Blaze Makoid Architecture of Sagaponac,NY, G_space is preparing for a green roof with the best available waterproofing to use under a green roof.

The advantages of Hyload CTEM (Coal Tar Elastomeric Membrane)

its ability to be installed a a zero slope

its capacity to perform as a root barrier without any additional layers of material

the 2 ply 150 mil thickness

up to 25 year warranty and a service life to 40+ years

Non Toxic, VOC compliant

extremely durable and puncture resistant

Here is the step by step process used on this residence

A 1/8″ per foot is our recommendation to provide minimal pitch to the drains

To achieve a pitch, Pre cut tapered furring strips were installed over the existing deck that was framed flat.

5/8″ plywood was installed over the furring with roof drains cut out, followed by a layer of gypsum roof sheathing

Gypsum roof sheathing or Dens Deck provides a stable base for the Self Adhered CTEM that minimizes expansion and contraction of the plywood. USG SecureDeck used here is heavier and harder to cut, but easier when applying the base sheet of CTEM when repositioning is necessary.

Copper Roof Drains attached to roof deck and set on a full bed of Hyload structural sealant.

Neoprene Primer is rolled on to Gypsum Sheathing. This allows the adhesive on the base sheet to bond to the sheathing.

A square cut out is made around the roof drains creating a recessed sump for the drains. Hyload structural sealant is then applied to the edge of the square cutout.

Self adhering base sheet is installed.

Since temperatures were in the 90’s, the adhesive was extremely sticky and the roof bonded too fast. We could not even use rubber gloves because the would stick to the sheet making it hard release from our hands. If the edges are set down first bubbles are formed and are hard to roll out because the bond is so tight. Some sections were lifted to roll out bubbles here is the advantage of the USG decking board, It did not break apart while lifting and repositioning the sheet. When using Dens-deck if a section that needed to be repositioned or lifted, the facing and some of the gypsum core will also lift off and stick to the CTEM sheet, a big mess.

After the base sheet is installed the 90 mil top sheet was installed with a 2″ min over lap on seams, all heat welded

The top sheet is much easier to reposition if necessary, but in these temperatures the bond was instantly formed. In some areas the white backing sheet that usually releases and slips out from under the sheet easily, was melting to the adhesive, sticking and tearing underneath. Sheets had to be lifted to remove the backing so a full bond between the sheets takes place.